| aperitive | A compound that stimulates the appetite. (09 Oct 1997) |
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| Apert | Eugene, French paediatrician, 1868-1940. See: Apert's hirsutism, Apert's syndrome. (05 Mar 2000) |
| Apert syndrome | <syndrome> Apert (1906) defined a syndrome characterised by skull malformation (acrocephaly of brachysphenocephalic type) due to the premature closure of the cranial sutures and syndactyly of the hands and feet of a special type (complete distal fusion with a tendency to fusion also of the bony structures). The hand, when all the fingers are webbed, has been compared to a spoon and, when the thumb is free, to an obstetric hand. Two clinical categories are distinguished, a 'typical' acrocephalosyndactyly, to which Apert's name is appropriately applied and other forms lumped together as 'atypical' acrocephalosyndactyly. The feature distinguishing the two types is a middigital hand mass with a single nail common to digits 2-4, found in Apert syndrome and lacking in the others. A frequency of Apert syndrome of 1 in 160,000 births is estimated. Evidence suggests that Apert syndrome results from mutations in the gene encoding fibroblast growth factor receptor-2. Progressive synostosis occurs in the feet, hands, carpus, tarsus, cervical vertebrae, and skull, and proposed 'progressive synosteosis with syndactyly' is possibly a more appropriate designation. Clinical features: flat facies, shallow orbits, hypertelorism, narrow palate, craniosynostosis, brachysphenocephalic acrocephaly, syndactyly, broad thumb, broad great toe, single nail digits 2-4, variable mental retardation, corpus callosum and/or limbic malformations, fused cervical vertebrae. A skull X-ray can confirm the diagnosis. Treatment is surgical. Inheritance: autosomal dominant, paternal age effect. (05 Aug 1998) |
| Apert's hirsutism | Hirsutism caused by a virilizing disorder of adrenocortical origin. (05 Mar 2000) |
| Apert's syndrome | <paediatrics> A usually inherited disorder characterised by premature closing of the cranial suture lines resulting in a peaked shaped head and abnormal facial appearance. Since it is usually autosomal dominant one or both parents also have the disorder. Surgery is used to correct skull and facial abnormalities. Inheritance: autosomal dominant. (29 Dec 1997) |
| apertognathia | An open bite deformity, a type of malocclusion characterised by premature posterior occlusion and absence of anterior occlusion. Synonym: open bite. Origin: L. Apertus, open, + G. Gnathos, jaw (05 Mar 2000) |
| apertometer | Instrument for measuring the angular aperture of a microscope objective. (05 Mar 2000) |
| apertura | Synonym: aperture. Origin: L. Fr. Aperio, pp. Apertus, to open (05 Mar 2000) |
| apertura externa aqueductus vestibuli | The external opening of the vestibular aqueduct on the posterior surface of the petrous part of the temporal bone near the groove for the sigmoid sinus. Synonym: apertura externa aqueductus vestibuli. (05 Mar 2000) |
| apertura externa canaliculi cochleae | The external opening of the cochlear aqueduct on the temporal bone medial to the jugular fossa. Synonym: apertura externa canaliculi cochleae. (05 Mar 2000) |
| apertura lateralis ventriculi quarti | One of the two lateral openings of the fourth ventricle into the subarachnoid space at the cerebellopontine angle. Synonym: apertura lateralis ventriculi quarti, foramen lateralis ventriculi quarti, foramen of Key-Retzius, foramen of Luschka, Retzius' foramen. (05 Mar 2000) |
| apertura mediana ventriculi quarti | The large midline opening in the posterior inferior part of the roof of the fourth ventricle, connecting the ventricle with the cerebellomedullary cistern. Synonym: apertura mediana ventriculi quarti, arachnoid foramen, Magendie's foramen, median aperture of the fourth ventricle. (05 Mar 2000) |
| apertura pelvis inferior | The lower opening of the true pelvis, bounded anteriorly by the pubic arch, laterally by the rami of the ischium and the sacrotuberous ligament on either side, and posteriorly by these ligaments and the tip of the coccyx. Synonym: apertura pelvis inferior, apertura pelvis minoris, fourth parallel pelvic plane, pelvic outlet, pelvic plane of outlet, plane of outlet. (05 Mar 2000) |
| apertura pelvis minoris | The lower opening of the true pelvis, bounded anteriorly by the pubic arch, laterally by the rami of the ischium and the sacrotuberous ligament on either side, and posteriorly by these ligaments and the tip of the coccyx. Synonym: apertura pelvis inferior, apertura pelvis minoris, fourth parallel pelvic plane, pelvic outlet, pelvic plane of outlet, plane of outlet. (05 Mar 2000) |
| apertura pelvis superior | The upper opening of the true pelvis, bounded anteriorly by the pubic symphysis and the pubic crest on either side, laterally by the iliopectineal lines, and posteriorly by the promontory of the sacrum. Synonym: apertura pelvis superior, aditus pelvis, first parallel pelvic plane, pelvic brim, pelvic inlet, pelvic plane of inlet, plane of inlet. (05 Mar 2000) |